Conventionally, ICT equipment such as a server device is installed in a machine room equipped with air conditioning, and is operated in an environment of an almost constant temperature in most cases. However, in order to reduce investment cost and operating cost of a machine room, attention is focused on a machine room where outside air is taken in, which is used to cool the inside of ICT equipment. A room temperature of a machine room utilizing outside air varies widely, compared with that of a machine room equipped with air conditioning. As such, it is desired that ICT equipment also has a function of controlling the internal temperature by itself.
As ICT equipment having a function of controlling the internal temperature, one disclosed in JP 2011-151131 A (Patent Document 1) has been known, for example. The server device (ICT equipment) disclosed in Patent Document 1 includes a cooling fan, an intake air temperature sensor which detects a temperature of intake air, a component temperature sensor which detects a temperature of an electronic component arranged inside the device, and a controller which controls the number of rotations of the cooling fan. The controller controls the number of rotations of the fan based on the detection result of the intake air temperature sensor and the detection result of the component temperature sensor. More specifically, the controller controls the number of rotations of the cooling fan in such a manner that the number of rotations of the cooling fan becomes higher as the intake air temperature is higher based on the detection result of the intake air temperature sensor, until the detection results of all component temperature sensors become a first threshold or smaller. When the detection results of all component temperature sensors become the first threshold or smaller, the controller controls the number of rotations of the cooling fan in such a manner that the number of rotations of the cooling fan becomes higher as the detection results of the component temperature sensors are higher based on the detection results of the component temperature sensors, until the detection results of all component temperature sensors become a second threshold (first threshold<second threshold).    Patent Document 1: JP 2011-151131 A
According to the technology disclosed in Patent Document 1, the internal temperature of ICT equipment can be controlled without depending on air conditioning. However, with the technology disclosed in Patent Document 1, there is a possibility that damage or malfunction of electronic components is caused if the intake air temperature drops sharply. As such, with the technology disclosed in Patent Document 1, if the intake air temperature drops sharply, there is a possibility that condensation occurs on the inner wall of the casing of the hard disk drive, which may induce rust so that damage or malfunction of the hard disk drive may be caused. In general, as a casing of a hard disk drive has air tightness of some extent, even if the intake air temperature drops sharply, the internal temperature of the casing of the hard disk drive will not drop sharply. As such, a large temperature difference is caused between the internal temperature of the casing of the hard disk drive and the inner wall temperature of the casing, which may cause condensation. It should be noted that if the temperature changes sharply, there is also a possibility that rust is generated due to condensation on other electronic components so that damage or malfunction of the electronic components may occur.